Bdtjtk

I am currently trying to implement LineChart mouse location zoom with ScrollEvent. I managed to do something but my problem is zooming into wrong direction. When my mouse stands on left side of lineChart, my zoom goes to right side of lineChart (symmetrical). Here is my code;

import javafx.application.Application;

import javafx.event.EventHandler;

import javafx.scene.Scene;

import javafx.scene.chart.LineChart;

import javafx.scene.chart.NumberAxis;

import javafx.scene.chart.XYChart;

import javafx.scene.input.ScrollEvent;

import javafx.scene.layout.BorderPane;

import javafx.stage.Stage;

import javafx.util.StringConverter;



public class ChartZoom extends Application {



    @Override

    public void start(Stage stage) {



        LineChart<Number, Number> chart = chart();

        final NumberAxis axis = (NumberAxis) chart.getXAxis();

        final double lowerX = axis.getLowerBound();

        final double upperX = axis.getUpperBound();



        chart.setOnScroll(new EventHandler<ScrollEvent>() {



            @Override

            public void handle(ScrollEvent event) {

                final double minX = axis.getLowerBound();

                final double maxX = axis.getUpperBound();

                double threshold = minX + (maxX - minX) / 2d;

                double x = event.getX();

                double value = axis.getValueForDisplay(x).doubleValue();

                double direction = event.getDeltaY();

                if (direction > 0) {

                    if (maxX - minX <= 1) {

                        return;

                    }

                    if (value < threshold) {

                        axis.setLowerBound(minX + 1);

                    } else {

                        axis.setUpperBound(maxX - 1);

                    }

                } else {

                    if (value < threshold) {

                        double nextBound = Math.max(lowerX, minX - 1);

                        axis.setLowerBound(nextBound);

                    } else {

                        double nextBound = Math.min(upperX, maxX + 1);

                        axis.setUpperBound(nextBound);

                    }

                }



            }

        });



        BorderPane borderPane = new BorderPane();

        borderPane.setCenter(chart);

        Scene scene = new Scene(borderPane, 800, 600);

        stage.setScene(scene);

        stage.show();

    }



    private LineChart<Number, Number> chart() {

        XYChart.Series series = new LineChart.Series<>();

        final String days = { "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday" };

        NumberAxis xAxis = new NumberAxis(0, days.length - 1, 1);

        xAxis.setAutoRanging(false);

        xAxis.setTickLabelFormatter(new StringConverter<Number>() {



            @Override

            public String toString(Number t) {

                int index = t.intValue();

                return (index >= 0 && index < days.length) ? days[index] : null;

            }



            @Override

            public Number fromString(String string) {

                throw new UnsupportedOperationException("Not supported yet.");

            }

        });

        NumberAxis yAxis = new NumberAxis();

        final LineChart<Number, Number> sc = new LineChart<>(xAxis, yAxis);

        sc.setCreateSymbols(false);

        sc.setPrefSize(1200, 210);

        series.setName("Line Chart Series");

        sc.getData().add(series);

        series.getData().add(new LineChart.Data(0, 23));

        series.getData().add(new LineChart.Data(1, 57));

        series.getData().add(new LineChart.Data(2, 54));

        series.getData().add(new LineChart.Data(3, 44));

        series.getData().add(new LineChart.Data(4, 14));

        series.getData().add(new LineChart.Data(5, 35));

        series.getData().add(new LineChart.Data(6, 65));

        return sc;

    }



    public static void main(String args) {

        launch(args);

    }

}

Ok i just fixed it by changing 3rd if below

if (direction > 0) {

                    if (maxX - minX <= 1) {

                        return;

                    }

                    if (value < threshold) { // if(value > threshold)

                        axis.setLowerBound(minX + 1);

                    } else {

                        axis.setUpperBound(maxX - 1);

                    }

You can use jfxutils.

To quickly implement a zoom function to you current LineChart use the ChartPaneManager. Remember that zooming functionality only works for LineChart<Number, Number>

https://github.com/gillius/jfxutils/releases

    ChartPanManager panner = new ChartPanManager(lineChartPrices);

    //while presssing the left mouse button, you can drag to navigate

    panner.setMouseFilter(mouseEvent -> {

        if (mouseEvent.getButton() == MouseButton.PRIMARY) {//set your custom combination to trigger navigation

            // let it through

        } else {

            mouseEvent.consume();

        }

    });

    panner.start();



    //holding the right mouse button will draw a rectangle to zoom to desired location

    JFXChartUtil.setupZooming(lineChartPrices, mouseEvent -> {

        if (mouseEvent.getButton() != MouseButton.SECONDARY)//set your custom combination to trigger rectangle zooming

            mouseEvent.consume();   

    });